In production or packaging lines, it is common practice for articles to be caused to transit from a first workstation to a second workstation via one or more intermediate conveyors. Generally, such conveyors have a working length that is constant, and the path followed by the articles they transport does not vary.
Nevertheless, under certain circumstances, it is necessary to adapt the path length of the articles as a function of particular production or maintenance constraints.
For example, in the above-mentioned situation, when the second workstation is stopped while the first workstation continues to operate normally, it is necessary to be able to store temporarily a certain number of articles upstream from the second workstation during the time that it is stopped.
Movement devices are already known that enable the number of articles that can be transported at a given time t between first and second workstations to be increased in a continuous manner, by continuously varying the length of the path traveled by the articles. Document U.S. Pat. No. 6,152,291 describes an example of a device enabling articles from an inlet conveyor to be deflected towards an adjacent outlet conveyor that is driven in the opposite direction, with the distance traveled by each article on the inlet conveyor and on the outlet conveyor being adaptable depending on requirements. To achieve that object, the device has a rotary wheel located in an empty space situated between the two conveyors, and a guide fastened to the rotary wheel and flush with the surfaces of the two conveyors, the guide being substantially circular and wide enough to deflect all of the articles from the inlet conveyor towards the wheel and from the wheel towards the outlet conveyor. The wheel is arranged in such a manner as to be capable of being moved in the longitudinal direction of said conveyors so as to vary the working lengths of the conveyors, i.e. the lengths over which the articles can be transported. By increasing the total length of the belt on which the articles can be placed, the number of articles that can be transported at a given instant t between the inlet conveyor and the outlet conveyor is increased.
The device described in document U.S. Pat. No. 6,152,291 enables the path length of the articles to be varied but it requires at least two conveyors to be used for that purpose together with an intermediate rotary wheel and a guide enabling the articles to be deflected from the first conveyor to the second. The drawback of such a device lies in the need to cause the articles to transit over a plurality of transport mechanisms, thereby increasing the risk of damaging the articles, and above all running the risk of requiring rate of throughput to be slowed down.